Counting circuit using multiple position beam switching tubes



1958 SIN-PlH FAN ETAL 2,843,546

K COUNTING CIRCUIT USING MULTIPLE POSITION BEAM SWITCHING TUBES Filed Feb. 1, 1954 4 Sheets-Sheet 1 ENTORS -PiH FAN RUDOLPH A. COLA KWMQQ W AG ENT Aug. 19, I958 SIN'PIH FAN ET AL Filed Feb. 1, 1954 4 Sheets-Sheet 2 f-Tg. 5

INVENTORS SI N- PIH FAN RUDOLPH A. COLA AGENT Aug. 19, 1958 SIN-PIH FAN ET AL 2,848,646

COUNTING CIRCUIT USING MULTIPLE POSITION BEAM SWITCHING TUBES Filed Feb. 1, 1954 4 Sheets-Sheet 3 Flg. IO 44 @B 2! i b U 24 88 88 24 i I A ll I II J 100% I02 INVENTORS i SIN'PIH FAN n 7 K RUDOLPH A. COLA [Mia- M AGENT Aug. 19, 1958 SlN-PIH FAN ETAL 2,848,646

COUNTING CIRCUIT USING MULTIPLE POSITION BEAM SWITCHING TUBES 4 Sheets-Sheet 4 Filed Feb. 1, 1954 INVENTORS PI AN 0 A.COLA BY ATTORNEY United States Patent COUNTING CIRCUIT USING MULTIPLE POSITION BEAM SWITCHING TUBES Sin-pill Fan and Rudolph A. Cola, Philadelphia, Pa., as-

signors to Burroughs Corporation, Detroit, Mich, a corp oration of lvlichigan Application February 1', 1954, Serial No. 407,296

11 Claims. (Cl. SIS-8.6)

trodes, each spade electrode having a transverse cross sectional configuration, disposed around the cathode. Each of the spade electrodes is insulated from the others. A circular array of target electrodes surrounds the array of spade electrodes, and electrons passing through the space between the spades impinge on at least one of the target electrodes. In some magnetron type multiple position beam tubes an apertured sleeve-like anode member, which functions as an electrostatic shield, is disposed between the spades and the targets. Usually an external magnet is disposed around the tube to provide a magnetic field having lines of force permeating the tube and which are parallel to the cathode of the tube.

The spades and targets, and the sleeve-like anode, if the tube has one, are maintained at positive potentials with respect to the cathode under static operating conditions. Normally all spades are at the same positive potential, as are the targets. This provides an electrostatic field between the spades and targets and the centrally disposed cathode. Because the targets are disposed farther from the cathode than are the spades, the efiect on the electrostatic field in the cathode-spade region of a change in target potential is slight as compared with a similar change in potential on the spades.

The relative strength of the magnetic field and the static field is such that under static operating conditions substantially no electrons emitted from the cathode reach any of the outer electrodes. However, if one of the spade electrodes, for example, is lowered to near the cathode potential, the electrostatic field is distorted adjacent to that spade and the effect of the magnetic field is overcome to an extent, and an electron stream or beam is formed between the cathode and the spade having the lowered potential. Each spade has a load impedance,

the voltage drop across this impedance due to electron flow to the spade is sufficient to maintain the electron beam at that position even though the means referred to above for lowering the spade potential is removed. The spade impedance, of course, must have an appropriate value in order to provide the proper voltage drop to hold the beam at that spade. For a more complete description of the operation of tubes, of this general type, reference is made to the co-pending applications of S. P. Fan and Saul Kuchinsky, Serial No. 370,086, filed July 24, 1953, now Patent No. 2,721,955, and of Saul Kuchinsky, Serial No. 370,137, filed July 24, 1953, now Patent No. 2,764,- 711.

While the electron beam or stream may be advanced from position to position (spade-to-spade) by individu- ,7 2,848,646 Patented Aug. 19, 1958 ICC ally lowering the potential of successive spades, such an arrangement is not desirable for some applications, such as for pulse counters, for example. One means which has formerly been used to switch the beam from one position to another is pulsing the anode electrode in those tubes having that electrode. Pulsing of the anode has been accomplished by inserting a blocking oscillator in series with the anode supply potential source and applying the pulses to be counted to the control element (grid) of the blocking oscillator tube. The circuit parameters of the blocking oscillator are chosen to provide an output pulse whose duration is slimcient to advance the beam in the switching tube fromone position to another.

Pulsing of the anode to advance the beam in the switching tube, however, has some technical shortcomings. The most serious one is that the switching rate when thismethod of beam advancement is used is limited to a comparatively slow rate. This method of switchingthe beam often requires that external spade capacitors be used in order to facilitate the switching. I

For some applications it may be desirable to determine what length of time a particular potential existed in a circuit. Since the beam switching rate from position-toposition is known, it would be desirable to have a circuit means other than the beam stepping means must bepro vided. This additional means complicate the apparatus as well as making it more bulky and expensive. v An object of the present invention is to provide an improved means for and a method of advancing the electron beam in a multiple position beam switching tube.

Another object of this invention is to provide an improved means for and method of advancing the electron beam in a multiple position beam switching tube to any chosen beam position.

A further object of the present invention is to provide improved electron beam advancing and beam clearing means for a multiple position beam switching tube.

An additional object of this invention is to provide an improved means for rapidly advancing the electron beam in a multiple position beam switching tube.

Still another object of the present invention is to pro-1 vide improved, simplified, and economical electron beam advancing means for use in a multiple position beam switching tube.

Yet another object of the present invention is to provide electron beam advancing means, for use with a multiple position beam tube, which is more reliable. in operation than prior art beam advancing means.

A still further object of the present invention is to provide an improved means for cascading a plurality of mag-- netron type multiple position beam switching tubes.

In accordance with one aspect of the present invention, an electron tube is connected in series with the cathode of the multiple position beam switching tube, and the pulses to be counted are applied to a control element, which may be a grid, of the tube in the cathode circuit.

pendent on the duration of the pulse applied to the control element of the series tube.

Alternatively,'the beam may be advanced by raising the potential of all the spades and ,thus increase the potential between the'cathode and the'outer electrodes.

The invention as'well as additional objects and advantages thereof will be best understood from the following description when read in connection with the accompanying' drawings, inwhich:

* Fig; 1 is an isometric view, partly broken away,'of a multiple'position beam switching tube which is suitable for use with the'present invention;

' Fig.2 is a sectional View taken along the lines 2--2 of Fig. 1; v r v Fig. 3 is an isometric view, partly broken away, of. another type of multiple position beam switching tube 7 present invention wherein beam switching is accomplished by pulsing the spades ofv the beam switching tube;

Fig. 7 is a partial sectional view of the tube of Fig. 1

showing the beam being held at a spade;

Fig.8 is a partial sectional view of the tube of Fig. l showing how the beam fans out when either the spades or'the cathode is pulsed in accordance with the present invention;

. Fig. 9 is a partial sectional view of the tube of Fig. 1 showing the beam being'held 'onthe leading edge of the spade after advancing as a result of the tanning out or spreading of the beam as shown in Fig. 8;

Fig. 10 is a'schematic view-showing two multiple positionbeam switching'tubes connected in cascade in accordance with the 'present'invention; and

Fig. 11 is a schematic view of two multiple position beam switching tubes connected in cascade in accordance with the present invention wherein beam switching is accomplished as shown in Fig. 6. v y 1 Referring to Figs. 1 and 2, there is shown a multiple position beam' switching tube comprising, within an hermetically sealed envelope 22, a centrally disposed cathode 24 which as illustrated, is'of the indirectly heated type; Surrounding the cathode 24 is a cylindrical array of spades 26. The spades have a substantial U-shaped cross-section, are usually but not necessarily coextensive in length with the cathode 24, and are insulated one from another. The open edges of eachspade 26 extends generally radially away ,from the cathode 24. It should be realized that the spades 26 (or beam forming and directing electrodes, using the phrase loosely) may have other cross 'sectionalconfigurations, the-configuration illustrated being merely by way of example.

Surrounding the array of spades isan array of individual target electrodes 28. Each of the target electrodes,

' like the spade electrodes 26, is insulated from the others and is usually coextensive in lengthwith the cathode 24. The sides of each target electrode 28 are bent inwardly generally towards the cathode 24 and in such a manner that each side of target electrode 28 is interleaved with one side of a spade electrode. Mica insulating spacers 50 are provided to maintain the proper spacing between the various electrodes of the tube. Leads (not shown for the 'sakeof clarity in the drawing) are brought out'through the stem 32 of the tube to base pins 34. V

The magnetic field for the tube is provided by the ex- I ternal hollow cylindrical magnet 36 which surrounds the tube 20. The tube mountlassembly 38 shown in Figs. 3 and 4. illustrates a second typeof multiple position beam switching tube which is suitablelfor. use the present inpositions through which the beam will advance is de-' vention. The centrally disposed cathode 24 andthe array of spades 26 are as in the tube shown in Figs. 1 and 2, but an apertured or slotted sleeve-like anode 40 is disposed between the spades 26 and the array of targets 44. Each of the slots 42 in the anode 40 are aligned with the space between two adjacent spades 26. The targets 44 are disposed adjacent to the slots 42 of the anode 40 in order that electronswhich passthrough the slots 42 will impinge thereon. The mica insulating spacers 30 are used to hold the parts of the mount assembly 38 in proper spaced relationship. The mount assembly 38 may be mounted in the same manner as the tube 20 illustrated in Figs.'1 and 2, including the external magnet 36.

Fig; 5 illustrates one embodiment of the present invention in which the electron beam of the multiple position beam tube 20, which is the same type tube as that illustrated in Figs. 1 and 2, is advanced by pulsing the cathode 24a. A separate'spade impedance, illustrated as comprising a resistor 43, is conductively connected between a.

source of positive potential 46and each of thespades 26a. A separate targetimpedance 48iillustrated as being a resistor, is conductively connected between'a source .-of positive potential 50 and each of'the output target elec dividual target impedance 48. is'taken from an output terminal 52. The source of positive potential to which thespade and'target impedances' are connected may be either separate or common supplies. The spade or target impedances, or both, may be included withinthe tube envelope if desired. Further, as shown by the symbol B, a magnetic field is' provided around the tube 20k: as described in connection with Fig.1. I

An electron tube 54', illustrated as being a triode bu which could be of another type, has its anode 56 conductively connected to the cathode 24a of the beam switching tube 20a. The cathode 58 of the tube 54 is connected to ground through. the cathode impedance resistor 60.

The input pulse which is utilized to controlthe advancement of the electron beam or stream in the tube 20:: is applied to the grid 62 of the tube 54 across the grid resistor 64. b v

The operation of the tube 20a and the beam advancing means is this: The beam is'formed and indexed by index-' ing arrangement 112, shown in Figs. 10 and 11. Ohviously, these switches for a plurality of beam switching tubes could be gauged. The electron beam, or stream rests on the leading edge of .one .of'the spades 26a (see Fig. 7), the leading edge of the spade being that'edge of the spade'which extends in the direction of rotation of the electron beam 68; the direction of rotation (indicated by the arrow 66) being determined by the polarity of the magnetic field which surrounds the tube and extends therethrough. Y

When a positive pulse is applied to the grid 62 of the tube 54, the voltage between the anode of the tube 54 and ground decreases. r

Since the value of the cathode resistor 60 is such that.

the cathode 24a of the tube 20zz'is normally at volts when the spades 26a are at 250 volts, a reduction in the voltage drop betweenthe anode 56 of the tube 54 and ground will lower the potential of the cathode 24a (to which anode 56 is'connected) and thus etfectively increase the strength of the electrostatic field existing between the cathode 24a and the spades 26a.

The result of the increase in the strength of the electrostatic field existing between the cathode. 24a and spades 26a, which thereby changes the ratio of the respective strengths of the beam-controlling electric and magnetic fields, is thatthe electron beam 68, as shown in Fig.8,

tends to fan out, causing some of the electrons to im-' pinge on the spade 26a whichis the spade to which the electron beam is to advance. The electrons impinging on the spade 26a 'causea voltage drop across the spade resistor (not shown in Figs. 7 to 9),of that spade, causing the electron beamto transferor shift to spade 26a. The

The output signal developed across each in-' position of the electron beam, after it has advanced, is at the leading edge of the spade 2641' as shown in Fig. 9. It is assumed that the duration of the input pulse is such that the beam will advance only one position. The time required to advance the beam one position has been found in some tubes to be less than .1 microsecond. If the pulse duration is long, the fanning and switching of the beam from one position to the next position will be repetitive, and the tube will oscillate (the beam will advance around the tube at a rate determined by the circuit parameters) until the input pulse is ended. The beam will then remain locked in at the most advanced spade it was impinging on at the end of the input pulse.

Thus, since a finite (and readily determinable) time is required to advance the beam from one position to another and since with uniformly spaced stable positions of the beam, as determined by the spacing of the spade electrodes, the time for advancement from one such position to the next is constant, the width of an input pulse applied to grid 62 may be determined by counting the number of positions the beam advances during the period of such a pulse. Also, since the capacitance between the cathode 24a and the outer electrodes (spades and targets) is small due to the large spacing therebetween, the potential of the cathode may be changed rapidly and the rate of beam advancement in the tube 20a is increased over what would be practical by pulsing the anode 40 in a tube having such a sleeve-like anode located between the spades 26 and the targets 28.

In the embodiment of the present invention which is shown in Fig. 6, the electron beam of the tube 20a is advanced by ulsing the spade electrodes 26a. In the beam advancing arrangement of Fig. 6, the cathode 2411 may be connected to ground through a cathode resistor or directly to ground, as shown. The target electrodes 28a and their load resistors 48 are connected to a source or sources of positive potential as in the arrangement shown in Fig. 5. The spades 26a and their spade resistors 43 are connected to a source of positive potential, however, through a series resistor 74 through which all the spade current passes. A tube 70, which may be similar to the triode tube 54 shown in Fig. has its anode 72 connected to the spade end of the resistor 74, so that the current for the triode 70 also passes through the resistor 74. The cathode 76 of the tube 70 may be connected directly to ground as shown in Fig. 6. The grid 78 of the tube 70 is biased (through resistor 80 from bias source 82) to permit electron flow across the tube 70 in the absence of any other signal being applied to the grid. Thus, the tube 70 is normally conducting and the current passing therethrough produces a potential drop across the series resistor 74 in addition to the voltage drop across resistor 74 which occurs as a result of the spade current passing therethrough.

Because the grid 78 is biased, the input signal 84 (beam advancing pulses) is applied to the grid 78 through an isolating capacitor 86.

The operation of the system of Fig. 6 is similar'to that of Fig. 5 in that the part of the electron beam adjacent to the spades fans out and impinges on the advance spade when the electrostatic field between the cathode 24a and spades 26a is made stronger. In the system of Fig. 6, however, the electrostatic field between the spades 26a and cathode 24a is strengthened by momentarily raising the potential of all the spades 26a. It is understood that the tube 20a is also surrounded by magnetic field means as shown, for example, in Fig. 1.

It will be recalled that both the spade current and current from the triode tube 70 pass through the series resistor 74 and cause a voltage drop across resistor 74. In order to increase the electrostatic field strength between the cathode 24a and the spades 26a, negative pulses 84 are applied to the grid 78 of the triode 70, cutting off the triode 70, and causing the spade potential to momentarily rise because of the decreased voltage drop across the resistor 74.

It should be noted that the method of advancing the beam shown in Figs. 5 and 6 is quite different from the prior art method of beam advancement wherein the potential of the spade to which the beam is to be advanced is reduced, or by reducing the potential of the sleeve-like anode to advance the beam as previously mentioned.

When the beam advancing means shown in Figs. 5 and 6 is used in conection with the type of. tube shown in Figs. 3 and 4 the circuit connections are identical with those shown in Figs. 5 and 6 so far as spades, target electrodes and cathode are concerned, but the sleeve-like anode 4t) is connected to a source of positive potential. The beam advancing means of the present invention is, of course, applicable to other multiple position beam switching tubes of this general type. The tubes shown in Figs. 1 through 4 are only illustrated as examples of suitable types of beam switching tubes.

Fig. 16 shows two magnetron type multiple position beam switching tubes 20b, 200, connected in cascade in accordance with the present invention. Each of the tubes is of the type illustrated in Figs. 3 and 4. The connection to the tube electrodes of each tube are the same as in Fig. 5 except that the sleeve-like anode 40 is conductively connected to a source of positive potential, such as the battery 83. The input beam advancing pulse is applied to the terminal 92 and thus to the grid 94 of the tube 96 in the same manner as described in connection with Fig. 5. The input signal for the second tube 98 is taken from the 0 target 44' and is coupled to the grid 1% of the tube 98 through lead 102 and the pulse shaping network 194. Thus, each time the beam in tube 96, the units tube, impinges on the 0 target, the beam in the tube 280, the tens tube, advances one beam position. Further, several beam switching tubes may be connected in cascade without affecting the stability of operation of the arrangement. Thus, such an arrangement provides. a convenient counter means, the total which may be counted depending on the number of tubes which are cascaded;

The tubes and 98 are each biased by a battery 106 so that a positive pulse applied to the grid of either of the tubes 96, 98 causes a decrease in the resistance of the tube, thus decreasing the cathode voltage and causing the beam of the beam switching tube to advance as explained previously in connection with Fig. 5. .The biasing arrangement in Fig. 10 is convenient also for clearing the tubes, as a negative pulse applied to the grid 94 or 1120, or both will extinguish the beam in the respective tubes. If spade pulsing is used to advance the electron beam in tubes which are cascaded, the polarity of the diode in the pulse shaping network 134 should be reversed.

Fig. ll shows two magnetron type multiple position beam switching tubes connected in cascade in a manner similar to that shown in Fig. 10. Each tube is the type illustrated in Fig. 2, connected as in Fig. 6 for advancing the beam. increasing the potential of the common connection to impedance elements 43, thereby increasing the electrostatic field between cathode 24a and beam forming and directing electrodes 26a.

The beam may be reformed and indexed to zero position by lowering the potential of the spade electrodeat the index position to near to the cathode potential. This may be accomplished as shown by the indexing arrangement 112 which is provided for each tube. By similar provisions, the beam may be indexed to other positions in the tube. Other indexing means may of course be used.

it is likewise within the teaching of the present invention to cause the electron beam to advance by varying the strength of the magnetic field in the spade-cathode area. This me hod, however, may prove inconvenient for high speed switching and also because of the bulkiness of the magnetic field means which is required.

As hereinbefore described, it is the relative strength, of the magnetic field and of the static field, which determines whether electrons reach any of the outer electrodes.

The change in electrical field is provided by and form a beam. The fanning out of the beam by varying the potential of all spade electrodes relative to the cathode-and-thus upsetting this relative strength also has been described. Varying the magnetic field also would afiect this relative strength similarly to determine the beam configuration. It is the relative. stren th of magnetic and electric fields which determines beam configuration; To provide this variation in the magnetic field, many permanent-magnet and electromagnet devices are available.

What is claimed is:

1. Pulse counting apparatus comprising a succession of magnetron type multiple position beam switching vacuum tubes which utilize crossed electrostatic and magnetic fieldsin the operation thereof, each of said beam switch ing tubes having a thermionic cathode electrode, a piurality of separate beamforming and directing electrodes each having a beam locking impedance element, and at least onev target electrode, a source of potential, 'means for momentariliy changing the strength of said electrostatic field, said means including a separate electron tube associated with each beam switching tube, said electron tube having at least an anode, a control electrode and an electron emissive electrode, said anode and said electron emissive electrode being connected in series with an electrode of a beam switching tube and a connecting terminal of said source of potential, means for coupling an input signal to said electron tube, and means including a pulse shaping network interconnecting one target electrode of each of said beam switching tubes to the field changing means of the following tube of said succession of beam switching tubes to utilize the output signal of one target electrode of one beam switching tube as an input signal for switching the beam of said following beam switching tube.

2. Pulse counting apparatus comprising a plurality of magnetron type multiple position beam switching vacuum tubes which utilize crossed electrostatic and magnetic fields in the operation thereof, each of said beam switching tubes having a thermionic cathode electrode, a plurality of separate beam forming and directing electrodes each having a beam locking impedance element, and at least one target electrode, a source of potential, means for momentarily changing the strength of said electrostatic field, said means including a separate electron tube associated with each beam switching tube, said electron tube having at least an anode, a control electrode and an electron emissive electrode, said anode and said electron emissive electrode being connected in series with the cathode electrode of a beam switching tube and said source of potential, means for coupling an input signal to said electron tube, and means including a pulse shaping network interconnecting one target electrode of one beam switching tube to said input coupling means of another beam switching tube to utilize the output signal of one target electrode of one beam switching tube as an input signal for said another beam switching tube.

3. Pulse counting apparatus comprising a plurality of v magnetron type multiple position beam switching vacuum tubes which utilize crossed electrostatic and magnetic fields in the operation thereof, each of said beam switching tubes having a thermionic cathode electrode, a plurality of separate beam forming and directing electrodes each having a beam locking impedance element, and at least one target electrode, a source of potential, means for momentarily changing the strength of said electrostatic field, said means including a separate electron tube associated with each beam switching tube, said electron tube having at least an anode, a control electrode and an electron emissive electrode, said anode and said electron emissive electrode being connected in series with the beam forming and directing electrodes of a beam switchone-target electrode of one beam switching tube to said input coupling means of another-beam switching tube to utilize the output signals of one-target electrode of one cam-switching tube as an input signal for said another beam switching tube. I a a I Pulse counting apparatus comprising a plurality of magnetrontype multiple position beam switching tubes which utilize crossed electrostatic and magneticfieids in the operation thereof, each of said beam switching tubes having a thermionic cathode electrode, a plurality of separate beam forming and directing electrodes each having a beam locking impedance element, and at least one target electrode, a source of potential, means for momentaiily increasing the strength of said electrostatic field, said means including a separate electron tube associatedwith each beam switching tube, said electron tube having at least an anode, a control electrode and an electron emissive electrode, said anode and said electron emissive electrode being connected inseries with the cathode. electrode of a beam switching tube and a terminal of said sourceof potential, means for-coupling an input signal to the control electrode of said electron tube, and means including a pulse shaping network interconnecting one target electrode of one beam switching tube to said field increasingmeans of another beam switching tube to utilize the output signal of one target electrode of onebeam switching tube as an input signal for said another beam switching tube.

5. Pulse counting apparatus comprisinga plurality of magnetrontype multiple position beam switching tubes which utilize crossed electrostatic and magnetic fields in the operation thereof, each ofsaid beam switching tubes having a thermionic cathodeelectrode, a plurality of separate beam forming and directing electrodes each having a beam locking impedance element, and at least one target electrode, a source of potential, means for momentarily increasing the strength of said electrostatic field, said means including a separate electron tube associated with each beam switching tube, saidelectron tube having at least an anode, a control electrode and an electron emissive electrode, said anode and said electron emissive electrode being connected inseries with the beam forming and directing electrodes'of a beam switching tube and a terminal of said source of potential, means for coupling an input signal to the control electrode of said electron tube, and means including a pulse shaping network interconnecting one target electrode of one beam switching tube to said field increasing .means of another beam switchingftube to utilize the output signal of one target electrode of beam switching tube as an input signal for said another beam switching tube. Y

6. Pulse counting apparatus comprising a successionof magnetron type multiple position beam switching vacuum tubes which utilize crossed electrical and magnetic fields I in the operation thereof, each of said beam switching tubes having a cathode, a plurality of separate beam forming and directing electrodes, and at least one target electrode, a source, of electrical energy, a source of mag: netic flux, means for increasing. the ratio of the electrical field to the magnetic field in the total field existing between said cathode and said beam forming and directing electrodes, a separate electron tube associated with each beam switching tube, said tube having at least an anode, a control electrode and an electron emissive electrode, said anode and said electron emissive electrode being connected with said ratio increasing means and' with said source of electrical energy, means for coupling an input signal to said electron tube, and circuit means including a pulse shaping network interconnecting one target electrode of one beam switching tube to said ratio increasing means ofa following tube of said succession of beam switching tubes to convert an output D. C. signal of one beam switching tube to a pulsed signal useful as an input signal for another beam switching tube. 7. Means for advancing the electron beam 'in a magnetron type multiple position beam switching tube in which control of the beam is exercised jointly by crossed electric and magnciic fields and which has a cathode, an array of spaced-apart beam forming and directing electrodes positioned about the cathode on any one of which electrodes the beam can be locked, and terminals respectively in electrical connection with said cathode and said electrodes, comprising, circuit means for applying to said terminals 2. pulse of suitable polarity to increase the potential difference between the beam forming and directing electrodes and the cathode and of sufficient amplitude to increase the strength of the electric field relative to that of the magnetic field acting on the beam when locked on one of said electrodes to a degree causing spreading of the beam in the vicinity of said one electrode and the impingement in part thereof on a next adjacent one of said electrodes, with resultant switching of the beam to said adjacent electrode.

8. Means for advancing the electron beam in a magnetron type beam switching tube having crossed electrio and magnetic fields and an array of spaced-apart beam forming and directing electrodes disposed about a cathode comprising, in combination, means connected between the cathode and the array of beam forming electrodes to momentarily increase the strength of the electric field, a second similar magnetron type beam switching tube having an output and a pulse forming network connected to the output thereof, and means coupling the output pulse forming network of said second tube to the first mentioned means to increase the electric field strength of the first tube in response to a signal pulse received on the output of the second tube.

9. Electron discharge means for producing and directing an electron beam to cause selective impingement thereof on a plurality of spaced-apart target elements, comprising a magnetron type multiple position electron beam switching tube in which crossed electrical and magnetic fields form an electron beam and control the position and direction of advancement thereof and which tube has a cathode electrode and a plurality of separate beam forming and directing spade electrodes spaced substantially equidistantly from the cathode electrode, the spade electrodes defining successive stable positions of the beam in each of which a portion of the beam impinges on the position-defining electrode, together with beam-receiving target elements respectively associated with the spade electrodes and likewise substantially equidistantly spaced from the cathode electrode but more remote therefrom than the spade electrodes; and circuit means having a connection to one of said electrodes for applyin an input electrical pulse increasing the normal operating spade-cathode potential difference and thus increasing the ratio of the strength of the electrical field to that of the magnetic field acting on the beam, said increased ratio being sufficient to spread the outer extremity of the beam away from the spade electrode on which it impinges and cause at least partial impingement thereof on the spade electrode in the next adjacent beam position in the direction of beam advancement, with resultant switching of the beam to said next position.

10. Electron discharge means for producing and directing an electron beam to cause selective impingement thereof on a plurality of spaced apart target elements, comprising a magnetron type multiple position electron beam switching tube in which crossed electrical and magnetic fields form an electron beam and control the position and direction of ad 'ancement thereof and which tube has a cathode electrode and a plurality of separate beam forming and directing spade electrodes spaced substantially equidistantly from the cathode electrode, the spade electrodes defining successive stable positions of the beam in each of which a portion of the beam impinges on the position-defining electrode, together with beam-receiving target elements respectively associated with tie spade electrodes and likewise substantially equidistantly spaced from the cathode electrode but more remote therefrom than the spade electrodes; and circuit means including amplifying means having an input circuit and an output circuit which includes the spadecathode circuits of the tube for producing therein an increase in the normal operating spade-cathode potential difference upon the application of a pulse of a suitable polarity to the input circuit of the amplifying means and thereby producing an increase in the ratio of the value of the existing electric field to that of the magnetic field acting on the beam, said increased ratio being sufficient to spread the outer extremity of the beam away from the spade electrode on Which it impinges and cause at least partial impingement thereof on the spade electrode in the next adjacent beam position in the direction of beam advancement, with resultant switching of the beam to said next position.

11. Means for obtaining a digital measure of the duration of a pulse comprising, a magnetron type multiple position electron beam switching tube in which control of the beam is exercised jointly by crossed electric and magnetic fields and wherein the beam can be caused to advance in a predetermined direction determined by said fields and in like time periods through a plurality of counting positions each defined by a beam forming and directing spade electrode on which the beam impinges at least in part when in the position defined thereby, advancement of the beam in said direction occurring through an increase above a normal operating value of the electric field sufi'icient to cause spreading of the beam beyond the width thereof for static positioning at one of said positions and the simultaneous impingement thereof in part on the next adjacent spade electrode in said direction, said tube having input pulse receiving terminals in electrical circuit connection with means therein, including said spade electrodes, controlling the strength of the electric field, and means for applying to said terminals for measurement purposes a pulse of definite limited duration having a suitable polarity and a sufiicient amplitude to increase the strength of the electric field and cause spreading of the beam in the foregoing manner during the entire period thereof, the number of counting positions passed through by the beam during the period of the pulse constituting a digital measure of the duration thereof.

References (Jited in the file of this patent UNITED STATES PATENTS 2,404,920 Overbeck July 30, 1946 2,540,654 Cohen Feb. 6, 1951 2,591,997 Backmark Apr. 8, 1952 2,599,949 Skellett June 10, 1952 

